Systems, methods and apparatus for protecting power distribution feeder systems

ABSTRACT

A power distribution feeder system includes a plurality of power sources, a plurality of switching components coupled to the power sources by a plurality of line sections, and an IED coupled to each switching component and configured to monitor any line section coupled to the switching component, each IED containing protection logic configured to detect a jump in current on a faulted line section, communicate the jump in current to other IEDs coupled to the faulted line section, receive information from the other IEDs coupled to the faulted line section regarding any jump in current detected by the other IEDs, employ the received information from the other IEDs to confirm a fault in the faulted line section, and issue a trip command to isolate the faulted line section based on the current jump detected by the IED and current jump information received from other IEDs coupled to the line section.

The present application claims priority from U.S. Provisional PatentApplication Ser. No. 61/619,965, filed Apr. 4, 2012 and titled“Transforming a Peer to Peer to Peer RMS or Jump Detector” and U.S.Provisional Patent Application Ser. No. 61/619,972, filed Apr. 4, 2012and titled “Transforming a Peer to Peer to Peer RMS or Jump DetectorType Differential Function,” each of which is hereby incorporated byreference herein in its entirety for all purposes.

FIELD

The present application relates to power distribution feeder systems,and more specifically to systems, methods and apparatus for protectingpower distribution feeder systems.

BACKGROUND

Protection of power distribution systems involves detecting, locatingand removing faults from the power systems. Conventional protectionmethods for automated power distribution feeder systems employ complexadaptive time-coordinated overcurrent schemes. Selective tipping toisolate faulted line sections is achieved through a time-coordination ofovercurrent functions of downstream devices. These protection systemsare typically used for static feeder topologies; and slight variationsto feeder topology further increase complexity.

Conventional protection devices may provide about four to eight settinggroups to address operation in different topologies. Calculating thetime-coordinated I-V curves for these multiple setting groups iscomplicated and costly. Highly accurate information regarding feedercharacteristics must be gathered to calculate the required coordinatedovercurrent settings for a feeder system. If the feeder system is to becompletely automated, so that the feeder topology may change between allpossible switching topologies, the number of time-coordinated settinggroups may exceed the available setting groups in the protectiondevices.

As such, a need exists for improved systems, methods and apparatus forprotecting power distribution feeder systems.

SUMMARY

In some embodiments, a power distribution feeder system is provided thatincludes (1) a plurality of power sources; (2) a plurality of switchingcomponents coupled to the power sources by a plurality of line sections;and (3) an intelligent electronic device (IED) coupled to each switchingcomponent and configured to monitor any line section coupled to theswitching component, each IED containing protection logic configured to(a) detect a jump in current on a faulted line section; (b) communicatethe jump in current to other IEDs coupled to the faulted line section;(c) receive information from the other IEDs coupled to the faulted linesection regarding any jump in current detected by the other IEDs; (d)employ the received information from the other IEDs to confirm a faultin the faulted line section; and (e) issue a trip command to isolate thefaulted line section based on the current jump detected by the IED andcurrent jump information received from other IEDs coupled to the linesection.

In some embodiments, an IED is provided for use in a power distributionfeeder system having a plurality of power sources and a plurality ofswitching components coupled to the power sources by a plurality of linesections. The IED includes protection logic configured to (a) detect ajump in current on a faulted line section; (b) communicate the jump incurrent to other IEDs coupled to the faulted line section; (c) receiveinformation from the other IEDs coupled to the faulted line sectionregarding any jump in current detected by the other IEDs; (d) employ thereceived information from the other IEDs to confirm a fault in thefaulted line section; and (e) issue a trip command to isolate thefaulted line section based on the current jump detected by the IED andcurrent jump information received from other IEDs coupled to the linesection.

In some embodiments, a method is provided for isolating a fault in apower distribution feeder system having a plurality of power sources anda plurality of switching components coupled to the power sources by aplurality of line sections. The method including (1) providing an IEDcoupled to each switching component and configured to monitor any linesection coupled to the switching component; and (2) employing a firstIED to (a) detect a jump in current on a faulted line section; (b)communicate the jump in current to other IEDs coupled to the faultedline section; (c) receive information from the other IEDs coupled to thefaulted line section regarding any jump in current detected by the otherIEDs; (d) employ the received information from the other IEDs to confirma fault in the faulted line section; and (e) issue a trip command toisolate the faulted line section based on the current jump detected bythe first IED and current jump information received from other IEDscoupled to the line section. Numerous other embodiments are provided.

Numerous other aspects are provided. Other features and aspects of thepresent invention will become more fully apparent from the followingdetailed description, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram of an example mesh-connected distributionfeeder provided in accordance with various embodiments.

FIG. 2 is an example embodiment of an intelligent electronic device(IED) in accordance with various embodiments.

FIG. 3A is a schematic diagram of example input/output connectionsbetween IEDs of FIG. 1 in accordance with various embodiments.

FIG. 3B is a schematic diagram of example input/output connectionsbetween other IEDs of FIG. 1 in accordance with various embodiments.

FIG. 4 is a schematic diagram of example protection logic for faultdetection and protection in accordance with various embodiments.

FIG. 5 is a schematic diagram of example jump inhibit logic provided inaccordance with various embodiments.

FIGS. 6A-6B are schematic diagrams of example positive jump pickup logicprovided in accordance with various embodiments.

FIGS. 7A-7B are schematic diagrams of example negative jump pickup logicprovided in accordance with various embodiments.

FIGS. 8A-8B are schematic diagrams of example dead end pickup logicprovided in accordance with various embodiments.

FIGS. 9A-9B are schematic diagrams of example pickup confirmation logicin accordance with various embodiments.

FIGS. 10A-10B are schematic diagrams of example low load equation logic,87L general pickup logic and 87L/67L selection logic provided inaccordance with various embodiments.

FIGS. 11A-11B are schematic diagrams of example fault confirmation logicin accordance with various embodiments.

FIG. 12 is a schematic diagram of example trip logic in accordance withvarious embodiments.

FIG. 13 is a schematic diagram of a first example of a faultedmesh-connected distribution feeder provided in accordance with variousembodiments.

FIG. 14 is a schematic diagram of a second example of a faultedmesh-connected distribution feeder provided in accordance with variousembodiments.

FIG. 15 is a schematic diagram of a third example of a faultedmesh-connected distribution feeder provided in accordance with variousembodiments.

FIG. 16 is a schematic diagram of a fourth example of a faultedmesh-connected distribution feeder provided in accordance with variousembodiments.

DETAILED DESCRIPTION

As described in U.S. Patent Application Publication No. US2011/0144931,published Jun. 16, 2011 and titled “Method and Apparatus for High-SpeedFault Detection In Distribution Systems,” which is hereby incorporatedby reference herein in its entirety for all purposes, a powerdistribution system may include intelligent electronic devices (IEDs)distributed throughout the power distribution system that monitor andcommunicate status information, such as current and/or voltage levels,between one another in a peer-to-peer or similar configuration. The IEDsmay employ a differential function to compare electrical quantitiesand/or other information entering and leaving protected zones, andcommunicate with one another to provide fast and accurate fault locationinformation. This may allow for rapid fault detection.

In some embodiments described herein, IEDs and/or differential functionsmay be employed to allow rapid disconnection of faulted line sections ofa power distribution feeder system without interrupting, or minimizinginterruption to, non-faulted line sections. Specifically, high speedfault detection through use of IEDs and/or differential functions may betransformed into and/or otherwise used as a protective function for apower distribution system to rapidly isolated a faulted line sectionwithout interrupting, or minimizing interruption to, non-faulted linesections.

The above described protection function, also referred to herein as“differential protection” may protect either mesh or loop connectedpower distribution feeders with multiple line sections and protectionpoints, equipped by IEDs. Differential protection may provide fastand/or selective fault location without the need of complicatedcoordinated groups of overcurrent settings. The protection algorithm maybe based on fast, real-time detection of dynamic changes in the analogvalues, where increase or decrease of measured current is converted to a“Positive Jump” logical signal or a “Negative Jump” logical signal,respectively. These signals may be communicated to other IEDs connectedto the same line section of the power distribution feeder system. Forexample, in some embodiments, positive and/or negative jump signals maybe transmitted between IEDs over an internet protocol (IP) basedcommunication network using the IEC 61850 standard peer-to-peercommunication protocol or another suitable protocol. Each IED mayinclude protection logic, which analyzes incoming data from other IEDs,and in some embodiments, operates the primary switching equipment whenlogical equations of the protection logic are fulfilled.

FIG. 1 is a schematic diagram of an example mesh-connected distributionfeeder 100 provided in accordance with various embodiments. Withreference to FIG. 1, the feeder 100 includes a plurality of linesections 102 a-102 g for distributing electrical power from one or moresources 104 a-c to a plurality of loads (not shown). More or fewer linesections and/or sources, and/or different topologies may be employed(e.g., loop-connected feeders). Line section lengths are merely forillustrative purposes.

Line section 102 a connects source 104 a to first breaker 106 a, linesection 102 b connects source 104 b to second breaker 104 b, and linesection 102 c connects source 104 c to third breaker 106 c. Line section102 d connects first breaker 106 a, first recloser 108 a, second breaker106 b and second recloser 108 b. Line section 102 e connects firstrecloser 108 a to third recloser 108 c. Line section 102 f connectsthird recloser 108 c to third breaker 106 c. Line section 102 g mayconnect second recloser 108 b to a load, an additional recloser, abreaker or another electrical component (not shown). Any other suitableelectrical components may be employed. In the embodiment of FIG. 1,breakers and reclosers are “closed” if shaded and “opened” if notshaded.

The feeder 100 includes a plurality of IEDs 110 a-e (P1-P6). Anysuitable IED may be employed, such as an RMS detector, a jump detectoror the like. IED 110 a (P1) is coupled to first breaker 106 a, IED 110 b(P2) is coupled to first recloser 108 a, IED 110 c (P3) is coupled tosecond breaker 106 b, IED 110 d (P4) is coupled to second recloser 108b, IED 110 e (P5) is coupled to third recloser 108 c, and IED 110 f (P6)is coupled to third breaker 106 c. Example IEDs are described furtherbelow.

IEDs 110 a-f may communicate with each other using wired and/or wirelesscommunication, and any suitable protocol. In some embodiments, IEDs 110a-f use a wireless or wired IP-based communication network for dataexchange. To reduce bandwidth requirements of the network, protectionlogic within the IEDs may operate with binary signals, and/or IEDs maycommunicate primarily (or only) with IEDs coupled to the same linesection. In FIG. 1, direction D1 is the direction extending from theleft side of an IED and direction D2 is the direction extending from theright side of an IED. For example, in this topology (FIG. 1) protectionlogic in the IED 110 b (P2) evaluates data from IEDs P1, P3 and P4 todetect a fault on line section 102 d (direction D1). To detect a faulton line section 102 e (direction D2), IED P2 operates primarily withsignals from IED P5. Protection related information from IED P6 is notrelevant and/or employed, because IED P6 is not connected to the sameline section as IED P2.

In general, any IED may be connected to and/or in communication with anynumber of other IEDs in any direction. In the embodiment of FIG. 1, amaximum of four IEDs are shown connected to a line section. More IEDsmay be employed by adding additional inputs, logic gates and/or computerprogram code to the IEDs. An example embodiment of an IED that may beused for one or more of the IEDs P1-P6 of FIG. 1 is described below withreference to FIG. 2.

FIG. 2 is an example embodiment of an IED 200 in accordance with variousembodiments. The IED 200 is configured to communicate with up to fourother IEDs coupled on either side D1 or side D2 of the IED 200. Asstated, the IED 200 may communicate with fewer or more IEDs. Tocommunicate with additional IEDs, the IED 200 would be provided withadditional inputs, logic and/or computer program code.

The IED 200 has a first set of inputs 202 a from up to four other IEDsrelating to a possible fault in a line section extending from directionD1 relative to IED 200, and a second set of inputs 202 b from up to fourother IEDs relating to a possible fault in a line section extending fromdirection D2 relative to IED 200. The IED 200 also includes a first setof outputs 204 a relating a possible fault along to a line sectionextending from direction D1 relative to IED 200, and a second set ofoutputs 204 b relating to a possible fault along a line sectionextending from direction D2 relative to IED 200. The various inputs andoutputs of IED 200 are described in detail below.

IED 200 includes protection logic 206 configured to perform theprotection functions described herein. Protection logic 206 may beimplemented in hardware, software or a combination of the same. Forexample, IED 200 may include one or more microprocessors,microcontrollers, programmable logic circuits (PLCs), applicationspecific integrated circuits (ASICs) or the like, capable of receiving,sending and/or processing data/control signals as described below. Insome embodiments, IEDs may communicate with one another using a protocolsuch as an IEC 61850 (open standard as a part of the InternationalElectrotechnical Commission's (IEC) Technical Committee 57 (TC57)reference architecture for electric power systems).

A high-speed communication system (such as fiber link, WiMax, WiFi, orother wired or wireless carrier technologies or a mixture thereof) maybe provided between IEDs for peer-to-peer communication. For example, anEthernet backbone may be linked over a twisted pair type copper cable,fiber or an Internet protocol (IP)-based radio system, broadband overpower line (BPL) or digital subscriber line (DSL). IED 200 may becapable of exchanging messages with other IEDs, for example, using GOOSE(Generic Object Oriented Substation Event) messages under the IEC61850Standard. Such a protocol may run over TCP/IP networks and/or substationLANs using high speed switched Ethernet. Peer-to-peer functionality viaIEC 61850 GOOSE messages provides not only binary data, but analogvalues as well.

The IED 200 may include, for example, a central processing unit, memory,and/or other circuitry for receiving input data, processing the data asdescribed herein and/or outputting data and/or control signals (e.g., aspart of logic 206, for example). Computer program code may be providedfor performing at least a portion of the methods described herein.

The IED 200 may, directly or via a recloser, circuit breaker or otherelectrical component, sense and/or interrupt fault currents as well asre-close and/or attempt to re-energize a line section. For example, theIED 200 may receive information from one or more current and/or voltagesensors, voltage transformers (VTs) and/or current transformers (CTs)208, to monitor the flow of current and/or power in a line section. TheCT 208 or other current and/or voltage sensor may provide input data toIED 200 for detecting positive and/or negative current jumps, forexample.

In some embodiments, the protection logic 206 in IED 200 may include oneor more of the inputs 202 a-202 b and/or outputs 204 a-204 b in Table 1below:

TABLE 1 Own Pos Jump= Output signal IED issues this signal when suddencurrent increase (Positive Jump) is detected in any phase Own Neg Jump=Output signal IED issues this signal when sudden current decrease(Negative Jump) is detected in any phase 87L PU D1= Output signal IEDissues this signal when 87L logic picks up in direction D1 87L PU D2=Output signal IED issues this signal when 87L logic picks up indirection D2 Own 52-b Status= Output signal IED issues this signal whenown primary switching device (Recloser or Breaker) is open Pos Jump D1X>Input signals Positive Jump is detected in direction D1 by IED X PosJump D2X> Input signals Positive Jump is detected in direction D2 by IEDX Neg Jump D1X> Input signals Negative Jump is detected in direction D1by IED X Neg Jump D2X> Input signals Negative Jump is detected indirection D2 by IED X PU D1X> Input signals 87L logic picks up indirection D1 signal from IED X PU D2X> Input signals 87L logic picks upin direction D2 signal from IED X 52-b Status of D1X> Input signalsSwitching Device is open signal from IED X in direction D1 52-b Statusof D2X> Input signals Switching Device is open signal from IED X indirection D2

Output signals from each IED are linked to appropriate inputs of all theother adjacent IEDs in direction D1 and direction D2. FIG. 3A is aschematic diagram of example input/output connections 300 a between IEDsP1-P4 of FIG. 1 in accordance with various embodiments. Otherconfigurations may be employed.

With reference to FIG. 3A, output signal “Own Pos Jump =” from IED P1 islinked to the “Pos Jump D11>” inputs of the IEDs P2 and P4. IED P3 isconnected to IEDs P1, P2 and P4 in direction D2, so IED P3 may considerdata from IEDs P1, P2 and P4 as signals from direction D2. Followingthis connection principle, “Own Pos Jump =” from IED P1 is connected tothe input “Pos Jump D21>” of IED P3.

FIG. 3B is a schematic diagram of example input/output connections 300 bbetween IEDs P2 and P5 of FIG. 1 in accordance with various embodiments.Other configurations may be employed. As shown in FIG. 3B, IED P2 isconnected to IED P5 in direction D1 (relative to IED P5), so IED P5considers signals from IED P2 as data from the direction D1. Followingthis connection principle, IED P2 receives signals from IED P5 as datafrom the direction D2 (relative to IED P2).

In some embodiments, the protection logic of each IED may perform sixmain actions to allow implementation of a protection function. Theseactions are described briefly below, primarily from the standpoint of anIED that detects a positive current jump on a line section to which theIED is connected. This IED is referred to below as the “initiating IED”and the other IEDs connected to the same line section are referred to as“responding IEDs”. The six actions of the protection logic may include:

(1) Jump Detector Inhibit—if the initiating IED detects a positive jumpin current, the protection logic of the initiating IED will not respondto a subsequent negative jump in current; in general, in someembodiments, any IED that responds to a positive current jump will notrespond to a subsequent negative current jump, and any IED that respondsto a negative current jump will not respond to a subsequent positivecurrent jump (during a protection function cycle); each IED connected toa line section that detects a positive or negative current jumpcommunicates the current jump to other IEDs connected to the linesection;

(2) 87L Pickup Communication—the protection logic of the initiating IEDissues a fault detection signal, referred to as an “87L pickup signal”,to other (responding) IEDs to communicate when its logical conditionsare fulfilled for a fault in direction D1 or D2;

(3) 87L Pickup Confirmation—the protection logic of the initiating IEDreceives an 87L pickup signal from other (responding) IEDs when theirlogical conditions are fulfilled for a fault in direction D1 or D2;

(4) 87L Low Current Pickup Confirmation—if the protection logic of aresponding IED does not detect a negative current jump due to lightloading, the responding IED may still issue an 87L pickup signal to theinitiating IED (as long as the responding IED did not detect a positivecurrent jump); in response to the 87L pickup signal from the respondingIED, the initiating IED may issue an 87L pickup signal (despite havingnot received a negative current jump signal from the responding IED);

(5) 87L Fault Detection Confirmation—if the protection logic of theinitiating IED performed all relevant actions such that a fault isdetected in direction D1 or D2, the fault is confirmed from a groundand/or phase overcurrent measurement (e.g., to prevent a spurious faultor sudden change in load profile from initiating the protectivefunction); and

(6) Protection Trip—once the fault is detected and confirmed, theprotection logic of the initiating IED issues a trip command to isolatethe faulted line section.

Using the above six actions to detect a fault on a line section, theprotection logic of an initiating IED detects a positive jump incurrent, ignores any subsequent negative current jump and communicatesthe positive current jump to other IEDs connected to the same linesection (Action 1). Actions 3 and 4 are completed when other IEDsconnected to the same line section detect a negative current jump, or nocurrent jump if lightly loaded, and reply with an 87L pickup signal(which may merely be an echo signal if lightly loaded) to the other IEDsconnected to the line section (Action 3 and Action 4). When all 87Lpickup/echo signals are received by the protection logic of theinitiating IED, the protection logic confirms the fault with a groundand/or phase current measurement (Action 5). If the fault is confirmedby ground and/or phase current measurements (Action 5), the protectionlogic of the initiating IED issues a trip signal to cause the primaryswitching device associated with the IED to open. (Note that if twoPositive Jumps are detected for a line section, in some embodiments, theprotection logic recognizes this as an external fault.)

FIG. 4 is a schematic diagram of example protection logic 400 for faultdetection and protection in accordance with various embodiments.Protection logic 400 may be implemented, for example, in IED 200 (FIG.2) and/or IEDs P1-P6 (FIG. 1) as hardware, software or a combinationthereof as described. Protection logic 400 includes jump inhibit logic401 a, D1 protection logic 401 b, D2 protection logic 401 c and triplogic 401 d. As described below, jump inhibit logic 401 a reducespickups from spurious faults or post fault switching. D1 protectionlogic 401 b provides for fault detection in first direction D1 and D2protection logic 401 c provides for fault detection in a seconddirection D2. Trip logic 401 d may generate a trip signal that causes aswitching device to open in response to fault signals from protectionlogic 401 b or 400 c.

With reference to FIG. 4, protection logic 401 b and 401 c both includepositive jump pickup logic 402, negative jump pickup logic 404, dead endpickup logic 406, pickup confirmation logic 408, low load equation logic410, 87L general pickup logic 412, 87L/67L selection logic 414, blockcondition logic 416 and fault confirmation logic 418. D1 protectionlogic 401 b generates a fault signal (FAULT D1=) if it detects a faultin direction D1, and D2 protection logic 401 c generates a fault signal(FAULT D2=) if it detects a fault in direction D2. These fault signalsare fed into trip logic 401 d, which in turn may generate a trip signal(87L TRIP) that causes a switching device to open.

As stated, each IED in a feeder system may include protection logic 400that includes jump inhibit logic 401 a, D1/D2 protection logic 401b, 401c and trip logic 401 d. For example, in FIG. 1, IEDs P1-P6 may eachinclude such protection logic, which will allow each IED to open itsrespective switching device upon issuance of an 87L TRIP signal by theIED (e.g., breakers 106 a-c and/or reclosers 108 a-c).

In some embodiments, the protection logic 400 may perform theabove-described six actions of a protection function as follows:

(1) Jump Detector Inhibit—if the protection logic 400 detects a positivejump in current, the jump inhibit logic 401 a may block any subsequentnegative jump in current; likewise, if the protection logic 400 detectsa negative jump in current, the jump inhibit logic 401 a may block anysubsequent positive jump in current; the protection logic 400 alsocommunicates any current jump to other IEDs connected to the same linesection;

(2) 87L Pickup Communication—through positive jump pickup logic 402 and87L general pickup logic 412, the protection logic 400 may issue an 87Lpickup signal to other IEDs to communicate when its logical conditionsare fulfilled for a fault in direction D1 or D2;

(3) 87L Pickup Confirmation—through pickup confirmation logic 408, theprotection logic 400 may receive an 87L pickup signal from other IEDswhen their logical conditions are fulfilled for a fault in direction D1or D2;

(4) 87L Low Current Pickup Confirmation—through low load equation logic410 (and/or pickup confirmation logic 408), if the protection logic ofan IED does not detect a negative current jump due to light loading, an87L pickup signal may still be generated in response to an incomingpositive current jump signal from an IED so that lack of a negativecurrent jump due to light loading does not prevent operation of theprotective function;

(5) 87L Fault Detection Confirmation—through fault confirmation logic418, if the protection logic 400 performs all relevant actions such thata fault is detected in direction D1 or D2, the fault may be confirmedfrom a ground and/or phase overcurrent measurement (e.g., to prevent aspurious fault or sudden change in load profile from initiating theprotective function); and

(6) Protection Trip—once the fault is detected and confirmed, trip logic401 d may allow the protection logic 400 to issue a trip command toisolate the faulted line section.

Example embodiments of the various logic 401 a-418 are described belowwith reference to FIGS. 5-16. It will be understood that other logicfunctions may be employed to carry out one or more of actions 1-6 above.

FIG. 5 is a schematic diagram of example jump inhibit logic 401 aprovided in accordance with various embodiments. Jump inhibit logic 401a includes a positive jump detector 502 coupled to a first pulse timer504, and negative jump detector 506 coupled to a second pulse timer 508.Positive jump detector 502 may be any current or other detector thatgenerates a “positive jump” output signal when a measured currentexceeds a predetermined threshold. For example, the positive jumpdetector 502 may be set to output a binary 0 value if a measured currenton a line section remains below the predetermined threshold, and abinary 1 value if the measured current exceeds (jumps above) thepredetermined threshold. Multiple thresholds may be employed in someembodiments. Any suitable predetermined threshold(s) may be used.

The negative jump detector 506 may be similarly configured, but generatea “negative jump” output signal when a measured current falls below apredetermined threshold. For example, the negative jump detector 506 maybe set to output a binary 0 value if a measured current on a linesection remains above the predetermined threshold, and a binary 1 valueif the measured current drops (jumps) below the predetermined threshold.Multiple thresholds may be employed in some embodiments. Any suitablepredetermined threshold(s) may be used.

The output of positive jump detector 502 serves as the start input ofpulse timer 504, and the output of negative jump detector 504 serves asthe start input of pulse timer 508. The output of pulse timer 504 mayserve as the “own positive jump” signal for protection logic 400, whilethe output of pulse timer 508 may serve as the “own negative jump”signal for protection logic 400 (as described further below). The resetinput of pulse timer 504 is coupled to the output of pulse timer 508,and the reset input of pulse timer 508 is coupled to the output of pulsetimer 504 through an OR gate 510. A 52-b input may be employed toinhibit issuance of a negative jump signal if the IED's associatedelectrical component is opened.

In operation, if the positive jump detector 502 detects a positive jumpin current, a positive jump signal is output which sets the output ofpulse timer 504 to a high state (e.g., binary “1” for a predeterminedtime period). This provides an “own positive jump” signal to protectionlogic 400. The output of pulse timer 504 also resets pulse timer 508 andprevents pulse timer 508 from responding to any negative jump signaloutput from negative jump detector 506, at least while the output ofpulse timer 504 remains high. Thus, an “own negative jump” cannot begenerated while pulse timer 504 remains high. Likewise, a negative jumpsignal detected by negative jump detector 506 may prevent subsequentpositive jump signals from generating an “own positive jump” signalwhile “own negative jump” is high.

In some embodiments, the pulse timers 504 and 508 output pulses having apulse width of about 250 milliseconds, although larger or smaller pulsewidths may be employed.

As described above, jump inhibit logic 401 a may generate either an “ownpositive jump” or “own negative jump” signal in response to a positivejump or negative jump in current on a line section monitored by an IED.If positive jump detector 502 detects a positive jump in current, thejump inhibit logic 401 a may block any subsequent negative jump incurrent from generating an “own negative jump” signal; likewise, if thenegative jump detector 506 detects a negative jump in current, the jumpinhibit logic 401 a may block any subsequent positive jump in currentfrom generating an “own positive jump” signal. This feature may limitany over operation of the protection logic 400 due to complex orevolving faults, switching sequences, evolving loads, or the like.

In some embodiments, the protection logic 400 may operate with lowcurrents (e.g., about 3 pH), and voltage may not be required for thecorrect operation. To detect positive and negative current jumps, IEDsmay use any existing algorithm. For example several overcurrent andundercurrent thresholds may be applied. When current exceeds anyovercurrent threshold, an IED may issue an “Own Positive Jump=” signal.An “Own Negative Jump=” may be issued if current drops below anyundercurrent threshold.

Another algorithm might be based on the periodic comparison of thepresently measured RMS current value I_(tn) and a previously measuredvalue I_(tn-1), sampled a few power cycles before (e.g., about 16-50milliseconds). If the difference ΔI between two successive samplesexceeds a threshold value I_(jump), then the IED may detect a positivecurrent jump. A negative current jump may be detected if ΔI≦−I_(jump).Mathematically this equation maybe written as:

$\left\{ \begin{matrix}{{{\Delta \; I} = {{I_{tn} - I_{{tn} - 1}} \geq I_{jump}}},} & {{{{Own}\mspace{14mu} {Position}\mspace{14mu} {Jump}} = \left. 0\rightarrow 1 \right.};} \\{{{\Delta \; I} = {{I_{tn} - I_{{tn} - 1}} \leq {- I_{jump}}}},} & {{{Own}\mspace{14mu} {Negative}\mspace{14mu} {Jump}} = \left. 0\rightarrow 1. \right.}\end{matrix}\quad \right.$

FIG. 6A is a schematic diagram of example positive jump pickup logic 402for direction D1 provided in accordance with various embodiments.Positive jump pick logic 402, and the other logic described below, aredescribed with reference to pickups in direction D1 from up to four IEDdevices. It will be understood similarly configured logic may beemployed for pickups in direction D2 and/or from fewer or more IEDdevices. For example, FIG. 6B is a schematic diagram of example positivejump pickup logic 402 for direction D2 in accordance with variousembodiments.

With reference to FIG. 6A, in response to a positive current jump on aline section, positive jump pickup logic 402 receives an “Own Pos Jump=”signal from jump inhibit logic 401 a (FIG. 4 and FIG. 5). The “Own PosJump=” signal is fed to an AND gate 5. The positive jump signal is alsocommunicated to all other IEDs in the D1 direction, which in responsethereto, issue negative jump signals, or 52-b status signals, receivedby positive jump pickup logic 402 (FIG. 6). As shown in FIG. 6, positivejump pickup logic 402 may receive either negative jump signals or 52-bstatus signals from up to four devices D11-D14 (where the tens digitindicates direction and the units digit indicates device number aspreviously described). A 52-b status signal is issued when an IED'sprimary switching device, such as a recloser or breaker, is open.

The negative jump signals (“Neg Jump D11”, “Neg Jump D12”, etc.) and52-b Status signals from IEDs connected to the line section in directionD1 drive OR gates 1-4, the outputs of which are fed to AND gate 5 alongwith “Own Pos Jump=”. If a negative jump signal or high 52-b Statussignal is received from each IED connected to the line section indirection D1, AND gate 5 outputs a high logic state to 87L Generalpickup logic 412 (FIG. 10A) that drives OR gate 13 to generate an “87LPU D1=” signal. If there are fewer than four IEDs connected to the linesection in direction D1, the inputs “52-b Status of D12>”, “52-b Statusof D13>”, or “52-b Status of D14>” for the missing IED(s) may bereplaced with a logical “1” (high voltage state). Failure of any IEDconnected to the line section to communicate a negative jump signal or52-b status signal disables the output of AND gate 5.

FIG. 7A is a schematic diagram of example negative jump pickup logic 404for direction D1 provided in accordance with various embodiments.(Example negative jump pickup logic 404 for direction D2 is shown inFIG. 7B.) With reference to FIG. 7A, in response to a negative currentjump on a line section, negative jump pickup logic 404 receives an “OwnNeg Jump=” signal from jump inhibit logic 401 a (FIG. 4 and FIG. 5). The“Own Neg Jump=” signal is fed to OR gate 6 along with inverted “Own PosJump=”. If the “Own Neg Jump=” signal is high and/or no positive currentjump is detected, OR gate 6 outputs a high logic state to AND gate 8.Additionally, if at least one positive current jump signal (“Pos JumpD11”, “Pos Jump D12”, etc.) is received from an IED connected to theline section in direction D1, OR gate 7 outputs a high logic state.

As stated, AND gate 8 outputs a high logic state when (1) an IED detectsis a negative current jump or, due to light loading, detects only theabsence of a positive current jump; and (2) at least one positivecurrent jump is detected by an IED connected to the line section indirection D1. A high logic state from AND gate 8 is fed to 87L Generalpickup logic 412 (FIG. 10A) and drives OR gate 13 to generate an “87L PUD1=” signal.

If an IED is the only IED connected along direction D1 or D2, faultdetection and isolation are performed without information from thatdirection; and fault detection may be performed employing dead endpickup logic 406 (FIGS. 8A-8B).

FIG. 8A is a schematic diagram of example dead end pickup logic 406 fordirection D1 provided in accordance with various embodiments. (Exampledead end pickup logic 406 for direction D2 is shown in FIG. 8B.) Deadend pickup logic 406 is activated by setting “D End D1” to a high logicstate if an IED is not connected to any other IED in direction D1. ORGate 10 receives ground overcurrent (OC) pickup and phase OC pickupsignals from ground and phase overcurrent elements (not shown) whichmeasure ground current magnitude and phase at the line section to whichthe IED is connected. These current elements are employed to confirmfault detection. Thresholds for overcurrent may be set, for example,above maximum possible load current. In some embodiments, a ground OCelement measures neutral or zero sequence current and issues a “GroundOC PU” signal if ground current exceeds a predetermined threshold. Aphase OC element may operate similarly with phase currents, and issue a“Phase OC PU” if phase current exceeds a predetermined threshold. Insome embodiments, operation of dead pickup logic 406 may be delayed byintroducing a delay to the ground and phase OC elements to coordinatewith possible downstream devices.

In operation, dead end pickup logic 406 is activated by applying a highlogic state to tag “D End D1”. Thereafter, if a positive current jumphas been detected by any IED in direction D2 so that OR gate 9's outputis high, and either a ground or phase overcurrent condition has beendetected so that OR gate 10's output is high, AND Gate 11 activates andissues a logical “1” or high voltage state that is fed to 87L generalpickup logic 412 (FIG. 10A) to allow fault detection and confirmation asdescribed further below.

In some embodiments, an IED reliably detects a fault in a line sectiondirection D1 or D2, when the IED receives 87L pickup signals from allthe other IEDs connected to the line section in that direction (e.g.,all devices agree with the fault location). If any 87L pickup signal ismissing from any IED device connected to the line section in thedirection of interest, either the logical equation in that IED is notfulfilled or the communication network has been failed. In such cases, afault will not be located and protection will not trip to avoid any overoperation. Pickup confirmation logic 408 determines wither a pickupsignal has been received from all relevant IEDs.

FIG. 9A is a schematic diagram of example pickup confirmation logic 408for direction D1 in accordance with various embodiments. (Example pickupconfirmation logic 408 for direction D2 is shown in FIG. 9B.) Within thepickup confirmation logic 408, the 87L Pickup signals from all IEDsconnected to the line section along direction D1 are fed to AND Gate 12.AND gate 12 outputs a high logic state if all IEDs have issued a pickupsignal. The high voltage state is fed to 87L general pickup logic 412(FIG. 10A) to allow fault detection and confirmation as describedfurther below. Note that if less than four IEDs are connected alongdirection D1 relative to an IED, the remaining/unused pickup inputs tothe AND Gate 12 may be replaced by the logical “1” or high voltagestate.

In lightly loaded line sections or other instances, an IED may notdetect a negative jump current. However, in some embodiments, an IEDlocated downstream from a fault may receive positive jump informationfrom an upstream device (as this information is communicated to the IEDfrom the upstream IED) and may employ negative pickup logic 404 to issuean echo signal, informing the upstream IED that communication with theIEDs is operational, but due to lack of the information, the downstreamIED did not detect the fault (as no negative current jump was observed).For example, the tag of the upstream IED used for the 87L Pickup signalmay be employed for the echo signal. OR gate 6 of negative jump pickuplogic 404 (FIG. 7A) may issue a high voltage to AND gate 8 even if anegative current jump is not detected (assuming a positive current jumpis also not present). In the upstream IED, low load equation logic 410(FIG. 10A) employs AND Gate 16 to fulfill the low load equation if theupstream IED's own positive jump has been detected and the upstream IEDreceived all the pickup and/or echo signals from other IEDs in directionD1. Note that absent low load equation logic 410, no 87L pickup signalwould be generated by the upstream IED if one or more downstream IEDsfailed to detect a negative current jump. For example, assuming the 52-bStatus lines are low, one missing negative jump signal (“Neg Jump D11”,“Neg Jump D12”, etc.) would cause AND gate 5 (FIG. 6A) of positive jumppickup logic 402 to output a low signal. As no negative current jumpwould be detected following the positive jump in the upstream IED, theoutput of OR gate 13 (FIG. 10A) would be low and no 87L pickup signal orfault trigger could be generated. Low load equation 410 addresses suchcircumstances.

FIG. 10A is a schematic diagram of example low load equation logic 410,87L general pickup logic 412 and 87L/67L selection logic 414 indirection D1 provided in accordance with various embodiments. (Exampledirection D2 logic for these functions is shown in FIG. 10B.) As shownin FIG. 10A, 87L general pickup logic 412 receives inputs from AND gate5 of positive jump pickup logic 402 (FIG. 6A), AND gate 8 of negativejump pickup logic 404 (FIG. 7A), AND gate 11 of dead end pickup logic406 (FIG. 8A), AND gate 12 of pickup confirmation logic 408 (FIG. 9A)and AND gate 16 of low load equation logic 410.

87L General Pickup logic 412 issues an “87L PU D1=” signal to the otherIEDs in the direction D1 when logical equations are fulfilled forpositive jump pickup logic 402 or negative jump pickup logic 404. Whenall other IEDs in the direction D1 confirm the pickup (e.g., issue an87L pickup signal) through pickup confirmation logic 408, or if thelogic equation fulfills for dead end pickup logic 406 or if the low loadequation 410 fulfills, OR Gate 15 drives AND gate 17 of 87L/67Lselection logic 414.

87L/67L selection logic 414 is designed to switch between the protectivefunction described herein (“87L”) and another fault detection algorithm,such as use of directional overcurrent elements or any other faultdetection algorithm. 87L may be selected by setting “87L/67L Select”high so that AND gate 17 and OR gate 19 of 87L/67L selection logic 414pass the output of OR gate 15 of 87L general pickup logic 412 to faultconfirmation logic 418 (FIG. 11A). Alternatively, to select anotherfault detection algorithm (referred to as “67L”), 87L/67L select may beset low, disabling the output of OR gate 15 of 87L general pickup logic412 and passing the fault detection signal from another detectionalgorithm (“67L Fault D1=”) to fault confirmation logic 418 through ANDgate 18 and OR gate 19 of 87L/67L selection logic 414.

As stated, with 87L selected in 87L/67L selection logic 414, the faultdetection signal from OR gate 15 of 87L general pickup logic 412 is fedto fault confirmation logic 418 of FIG. 11A, which illustrates aschematic diagram of example fault confirmation logic 418 in directionD1 in accordance with various embodiments. (Example fault confirmationlogic 418 for direction D2 is shown in FIG. 11B.) As shown in FIG. 11A,the output of OR gate 15 of 87L general pickup logic 412 (FIG. 10A)drives a first input of AND gate 21 (FIG. 11A) of fault confirmationlogic 418. The second input of AND gate 21 is driven by a blockcondition signal from block condition logic 416. If no block conditionsexist, AND Gate 21 drives Timer 22 in the fault confirmation logic 418.

In some embodiments, 87L protection may be disabled manually orautomatically whenever a Manual Close signal, Inrush signal,Communication (Comms) Fault signal, System Fault signal, or >Block 87Lsignal is received by block conditions logic 416. These blockingconditions/signals are described below in Table 2. If any block signalis active, OR gate 20 of block condition logic 416 drives the output ofAND gate 21 of fault confirmation logic 418 low, disabling faultconfirmation.

TABLE 2 Manual Close = Manual Close signal may be a 500 ms pulse orother suitable pulse width, issued when a primary switching device hasbeen closed. Inrush Detected Inrush signal is active if a significantinrush current is detected due to energizing of a transformer on thefeeder. Comms Fault Comms Fault signal is active if an IED lostcommunication to any other IED in the system. System Fault System faultsignal is active if the protection logic (87L) already detected a faulton the feeder. >Block 87L By this tag 87L protection may be blocked by acontrol center or due to any other condition.

If no block conditions exist, and the 87L general pickup logic 412indicates a fault has been detected, AND Gate 21 of fault confirmationlogic 418 drives timer 22. When this timer is initiated, faultconfirmation is performed (e.g., OR gate 26 issues fault signal “FaultD1=” informing all IEDs connected to the line section that a fault hasbeen detected in direction D1.)

To ensure that the detected fault is not a spurious fault or detectionof sudden change in the load profile, the detected fault is confirmedfrom a ground overcurrent (OC) pickup signal or phase OC pickup signalfrom ground and phase OC elements (not shown) which measure groundcurrent magnitude and phase at the line section to which the IED isconnected. Thresholds for overcurrent may be set, for example, abovemaximum possible load current. In some embodiments, a ground OC elementmeasures neutral or zero sequence current and issues a “Ground OC PU”signal if ground current exceeds a predetermined threshold. A phase OCelement may operate similarly with phase currents, and issue a “Phase OCPU” if phase current exceeds a predetermined threshold. In someembodiments, current OC elements must pickup while timer 22 is running(as described below).

If Ground OC PU or Phase OC PU signals are present, OR Gate 23 sets theflip flop 25 through AND Gate 24 (assuming the output of timer 22 ishigh). Once flip flop 25 has been set, output Q becomes high (binary“1”), and OR Gate 26 issues a fault signal “Fault D1=” (confirmed faultdetected in direction D1). The fault is latched by flip flop 25 untilflip flop 25 is reset (e.g., flip flop 25 keeps “Fault D1=” high even iftimer 22 times out). Flip flop 25 can be reset by the tag “87L Res”locally at the IED or remotely from a control center, for example. Insome embodiments, OR Gate 26 also may issue the “Fault D1=” signal ifbinary tag “Set Fault D1” is activated to simulate fault detectionduring the testing of the system.

Once a fault is detected and confirmed, the protection logic 400 issuesa trip command to isolate the faulted line section. In some embodiments,the trip command may be issued only once. For example, if several autoreclose attempts are made, further trip commands may be issued byovercurrent protection logic (not shown).

FIG. 12 is a schematic diagram of example trip logic 401 d in accordancewith various embodiments. After a fault signal is detected, such asFault D1=from OR gate 26 (FIG. 11A) of fault confirmation logic 418 or asimilar Fault D2= signal (FIG. 11B) in the D2 direction, OR gate 57(FIG. 12) drives AND gate 58. Assuming the system is not in a simulationmode (e.g., “Simulation ON=” is low so that simulation mode isdisabled), AND gate 58 sends a logical high signal to the input D ofrise detector 59. With a positive jump current having been detected andgiven rise to the Fault D1= or Fault D2= signal, rise detector 59 thendrives AND gate 60, which sets flip flop 61. If either ground or phaseovercurrent elements detect/confirm ground or phase overcurrents (asidentified through OR gate 54), the set flip flop 61 will cause AND gate62 to output a high logic state, which serves as the trip command “87LTrip=”. This causes the primary switching device associated with the IEDto open. Once the primary switching device has been opened, “>52-b”status feedback input is set high (true), which resets the flip flop 61through OR gate 55. (Note that if a system fault is not present anymore,rise detector 56 may drive OR gate 55 to reset flip flop 61 and disableissuance of trip commands.)

An overcurrent is associated with a positive jump in current. In someembodiments, if both an overcurrent and negative current jump aredetected, a current reversal (rev.) is declared by issuance of “CurrentRev. Detected” by AND gate 53. This may occur if there an active loadsuch as a motor connected to a line section. The motor may act asgenerator or source and feed a fault for a short time period, forexample.

The trip command issued by trip logic 401 d causes primary switchingequipment, such as a circuit breaker or recloser, coupled to an IED toopen as shown, for example, in FIG. 2. In this manner, the faulted linesection is isolated.

Note that protection logic 401 c for direction D2 is essentiallyidentical to protection logic 401 b for direction D1, with the exceptionthat tags labeled D1 are replaced with tags labeled D2, and tags labeledwith D11, D12, D13 and D14 are replaced with tags labeled D21, D22, D23,and D24, respectively. Tags labeled D21, D22, D23 and D23, such as indead end pickup logic 406 (FIG. 8A) are replaced with tags labeled D11,D12, D13 and D14, respectively. This may be seen in FIGS. 6B, 7B, 8B,9B, 10B and 11B.

Example Operation of Protection Logic

Example operation of the protection logic 400 is described below withreference to FIG. 13, which is identical to FIG. 1 but with a fault 1300on line section 102 d. In this case, IED P1 sees a sudden currentincrease and issues an “Own Positive Jump=” signal (Action 2) to allother IEDs connected to line section 102 d (IEDs P2, P3 and P4). IEDs P2and P4 both see a sudden decrease of current and issue their “OwnNegative Jump=” signals. Inhibit jump logic 401 a prevents each IED fromissuing multiple current jump signals (Action 1). IED P3 is open anddoes not observe any current jump.

IED P2 detects a negative jump in current. In response to a positivejump signal from IED P1 (Pos Jump D11> in FIG. 7A), negative jump pickuplogic 404 (FIG. 7A) within IED P2 drives OR gate 13 (FIG. 10A) of 87Lgeneral pickup logic 412. This causes IED P2 to issue an “87L PU D1=”pickup signal (Action 2) to all IEDs connected in direction D1 (IEDs P1,P3, and P4). (Missing inputs may be tied to a high logical voltage “1”.)

IED P4 detects a negative jump in current. Logic behavior in the IED P4is similar to that of IED P2. In response to a positive jump signal fromIED P1 (Pos Jump D11>), negative jump pickup logic 404 within IED P4drives OR Gate 13 (FIG. 10A). P4 issues an “87L PU D1=” pickup signal(Action 2) to all IEDs (IEDs P1, P3, and P2) connected in the directionD1.

IED P3 is open, and does not observe any current jumps. Nevertheless IEDP3 receives the positive jump signal “Pos Jump D21>” signal from IED P1(FIG. 7B) and replies by sending pickup signal “87L PU D2=” (Action 2).This echo signal is employed to check validity of the communicationnetwork during the fault detection period. Negative jump pickup logic404 for direction D2 would perform this function because OR gate 6 (FIG.7B) has an inverted input connected to the “Own Positive Jump=” signal.If IED P3 detected a positive current jump, an echo signal would not besent along direction D2 by IED P3.

IED P1 receives the negative jump signals “Neg Jump D22>”, “Neg JumpD24>” from IEDs P2 and P4, respectively. Within positive jump pickuplogic 402 of IED P1, OR gates 2 and 4 (FIG. 6B) receive these inputs andoutput a high logic voltage. IED P3 provides its open status “52-bStatus of D23” to the OR Gate 3 instead of a negative jump signal.Missing links to the OR gate 1 are replaced by logical “1”. As allconditions for the AND Gate 5 are true, OR gate 13 (FIG. 10B) issues an87L PU D2= pickup signal to all the IEDs in the direction D2 (Action 2).

IED P1 receives 87L pickup signals from IEDs P2, P3 and P4, whichindicate these devices agree with the fault location on the line section102 d. Within IED P1, AND gate 12 (FIG. 9B) of pickup confirmation logic408 drives OR gate 15 (FIG. 10B) of 87L general pickup logic 412 throughAND gates 14 and 16 (Action 3). OR gate 15 makes AND gate 21 (FIG. 11B)active, if block conditions are not present at this moment. AND gate 21drives the pulse timer 22. Once timer has been started, AND gate 24waits for the Ground or Phase overcurrent elements to confirm the fault.These elements might have some definite time delay to avoid overreactiondue to spurious faults or lightning strikes. (Action 4 is not fulfilledbecause all negative current jumps or 52-b signals were received.)

If the fault is confirmed within the delay set by flip flop 22 (e.g.,150 milliseconds or another suitable delay), AND gate 24 sets the flipflop 25. As such, the fault is reliably detected and a fault event islatched by IED P1. OR gate 26 provides a “Fault D2=” signal for theinternal logic and control center (Action 5).

With reference to FIG. 12, OR gate 57 through AND gate 58 drives therise detector 59 in response to the Fault D2= signal. The pulse from therising output of rise detector 59 sets flip flop 61 through AND gate 60.Assuming a phase OC signal has been picked up, flip flop 61 sends thetrip command “87L Trip” through AND gate 62 to open circuit breaker 106a (FIG. 13). When the switching device associated with IED P1 has beenopened (e.g., when circuit breaker 106 a has opened), a “>52-b” statusfeedback input becomes high and resets flip flop 61 through OR gate 55.With circuit breaker 106 a opened, faulted section 102 d is isolatedfrom the source 104 a (Source S1).

Protection logic 400 in IEDs P2, P3, and P4 also detects the fault online section 102 d. However, a trip command is issued only by device P1because the trip logic operates only if a positive jump is detected,allowing AND Gate 60 (FIG. 12) to set flip flop 61.

Lightly Loaded Operation of Protection Logic

Consider the protection behavior in case of a fault in line section 102d when line section 102 g is lightly loaded and IED P4 does not anegative jump in current (FIG. 14). In this case, IED P1 sees a suddenincrease of the current and issues an “Own Positive Jump=” signal. IEDP2 sees a sudden current drop in the faulted phases and issues an “OwnNegative Jump=” signal. IED P3 is open and therefore does not detect anycurrent jump.

Logic behavior for IEDs P2 and P3 is the same as described above. IED P4receives a positive jump signal from IED P1, but detects no positive ornegative jump signal of its own. Nevertheless, IED P4 sends an echopickup signal “87L PU D1=” back in the direction D1 (because no positivejump is detected so OR gate 6 (FIG. 7A) becomes active along with ORgate 7 to drive AND gate 8 and OR gate 13 (FIG. 10A).

IED P1 receives the negative jump signal “Neg Jump D22>” signal from IEDP2 (FIG. 6B), but no negative jump from IED P4. Therefore OR gate 4 andAND gate 5 are inactive. Nevertheless IED P1 receives a “PU D22>” pickupsignal (FIG. 9B) from IED P2 and echo signals “PU D23>”, “PU D24>” fromIED P3 and P4 respectively, so AND gate 12 becomes active and drives theOR gate 15 through AND gate 16. IED P1 then operates as it is describedabove.

AND Gate 16 is designed to trigger the protection logic in cases inwhich a device fails to receive all negative jumps from other IEDs dueto a low load condition. In such cases the local protection logic may betriggered if at least all the pickups or echo signals has been receivedfrom the other IEDs.

Detection of Positive Jump by Multiple IEDs

FIG. 15 illustrates the power distribution feeder system 100 in which afault exists in line section 102 e in accordance with variousembodiments. Fault current is flowing through IED P1, but the protectionlogic of IED P1 should not operate because section 102 d is not faulted.

IEDs P1 and P2 see a sudden current increase and issue “Own PositiveJump=” signals. IED P4 sees a sudden decrease of current in the faultedphases and issues an “Own Negative Jump=” signal. IED P3 is open andtherefore does not detect any current jump.

IED P2 receives the positive jump signal from IED P1, but this signalwill not cause a pickup in direction D1 because IED P2 detects its ownpositive current jump (e.g., if a device detects its own positivecurrent jump, the device will not pickup in the direction from whichanother positive current jump signal has been received). In this caseIED P1 will not receive pickup signal “PU D22>” from IED P2, AND gate 12(FIG. 9B) in pickup confirmation logic 408 of IED P1 will remaininactive, and IED P1 will not detect a fault on the line section 102 d.For the same reason, IED P1 will not trip if a positive current jump hasbeen detected by IED P4 for a fault in line section 102 g.

For IED P2, OR gate 2 (FIG. 6B) has an open status signal from IED P5.When IED P2 detects its own positive current jump, AND gate 5 drives ORgate 13 to sends an “87L PU D2” pickup signal to the direction D2 (FIG.10B).

IED P5 receives the positive jump signal from IED P2 and sends an echopickup signal back, because no own current jump is detected. When IED P2receives this echo signal (“PU D22>”), AND Gate 12 (FIG. 9B) drives theAND Gates 14, 16 (FIG. 10B). This causes a fault detection in thedirection D2 and a trip command as described previously.

Dead End Pickup Operation

FIG. 16 illustrates the power distribution feeder system 100 in which afault exists in line section 102 g in accordance with variousembodiments.

IEDs P1 and P4 see a sudden current increase and each issue a “OwnPositive Jump=” signal. IED P2 sees a sudden decrease of current in thefaulted phases and issues an “Own Negative Jump=” signal. IED P3 is openand does not detect any current jump.

The fault conditions for IED P1 are not fulfilled because IED P4 detectsa positive jump downstream from IED P1. Actions 2, 3 and 4 are notperformed because IED P4 is not connected to the any other device in thedirection D2. Therefore dead end pickup logic 406 is employed (FIG. 8B).

A fault is detected in the direction D2 if IED P4 receives at least onepositive jump signal from the direction D1 and its own Ground or Phaseovercurrent element detects an overcurrent to confirm the fault. WhenIED P4 receives a positive jump signal “Pos Jump D11>” from IED P1 andits phase overcurrent element detects an overcurrent, OR gates 9 and 10of dead end pickup logic 406 (FIG. 8B) drive AND gate 11, whichactivates OR Gate 15 (FIG. 10B) in the 87L general pickup logic 412.Once OR Gate 15 is activated, and if no blocking conditions exist, IEDP4 detects the fault in the direction D2 and trips the primary switchingdevice (recloser 108 b).

Accordingly, while the present invention has been disclosed inconnection with the example embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claims.

The invention claimed is:
 1. A power distribution feeder system including: a plurality of power sources; a plurality of switching components coupled to the power sources by a plurality of line sections; an intelligent electronic device (IED) coupled to each switching component and configured to monitor any line section coupled to the switching component, each IED containing protection logic configured to: detect a jump in current on a faulted line section; communicate the jump in current to other IEDs coupled to the faulted line section; receive information from the other IEDs coupled to the faulted line section regarding any jump in current detected by the other IEDs; employ the received information from the other IEDs to confirm a fault in the faulted line section; and issue a trip command to isolate the faulted line section based on the current jump detected by the IED and current jump information received from other IEDs coupled to the line section.
 2. The system of claim 1 wherein the IEDs are configured to communicate at least one of wirelessly and peer-to-peer.
 3. The system of claim 1 wherein the switching components include at least one of reclosers and circuit breakers.
 4. The system of claim 1 wherein the protection logic of each IED is further configured to inhibit detection of a subsequent jump in current after detecting an initial jump in current.
 5. The system of claim 1 wherein the protection logic of each IED is configured to detect both positive and negative jumps in current on a faulted line section and to communicate positive and negative current jump information to other IEDs coupled to the line section.
 6. The system of claim 5 wherein each IED is further configured to generate a fault detection signal based on a positive current jump detected by the IED and negative current jumps detected by other IEDs coupled to the faulted line section.
 7. The system of claim 5 wherein the protection logic of each IED is further configured to confirm any positive jump in current detected by the IED by confirming receipt of negative current jump information from other IEDs coupled to the faulted line section.
 8. The system of claim 7 wherein the protection logic of each IED is further configured to generate a fault confirmation signal based on the confirmation of the positive current jump, and to communicate the fault confirmation signal to other IEDs coupled to the faulted line section.
 9. The system of claim 5 wherein the protecting logic of each IED is further configured to confirm any negative jump in current detected by the IED by confirming receipt of positive current jump information from at least one other IED coupled to the faulted line section.
 10. The system of claim 9 wherein the protection logic of each IED is further configured to generate a fault confirmation signal based on the confirmation of the negative current jump, and to communicate the fault confirmation signal to other IEDs coupled to the faulted line section.
 11. The system of claim 1 wherein the protection logic of each IED is further configured to confirm receipt of a fault confirmation signal from all other IEDs coupled to the faulted line section.
 12. The system of claim 1 wherein the protection logic of each IED is further configured to generate a fault confirmation signal if the IED does not detect either a negative current jump or a positive current jump in the faulted line section in response to communication of a positive current jump from another IED coupled to the faulted line section.
 13. The system of claim 1 wherein the protection logic of each IED is further configured to use at least one of a ground and a phase overcurrent measurement to confirm any fault detection determined based on negative and positive current jumps communicated between IEDs coupled to the faulted line section.
 14. An intelligent electronic device (IED) for use in a power distribution feeder system having a plurality of power sources and a plurality of switching components coupled to the power sources by a plurality of line sections, the IED comprising: protection logic configured to: detect a jump in current on a faulted line section; communicate the jump in current to other IEDs coupled to the faulted line section; receive information from the other IEDs coupled to the faulted line section regarding any jump in current detected by the other IEDs; employ the received information from the other IEDs to confirm a fault in the faulted line section; and issue a trip command to isolate the faulted line section based on the current jump detected by the IED and current jump information received from other IEDs coupled to the line section.
 15. The IED of claim 14 wherein the IED is configured to communicate with other IEDs at least one of wirelessly and peer-to-peer.
 16. The IED of claim 14 wherein the protection logic of the IED is further configured to inhibit detection of a subsequent jump in current after detecting an initial jump in current.
 17. The IED of claim 14 wherein the protection logic of the IED is configured to detect both positive and negative jumps in current on a faulted line section and to communicate positive and negative current jump information to other IEDs coupled to the line section.
 18. The IED of claim 17 wherein the IED is further configured to generate a fault detection signal based on a positive current jump detected by the IED and negative current jumps detected by other IEDs coupled to the faulted line section.
 19. The IED of claim 17 wherein the protection logic of the IED is further configured to confirm any positive jump in current detected by the IED by confirming receipt of negative current jump information from other IEDs coupled to the faulted line section.
 20. The IED of claim 19 wherein the protection logic of the IED is further configured to generate a fault confirmation signal based on the confirmation of the positive current jump, and to communicate the fault confirmation signal to other IEDs coupled to the faulted line section.
 21. The IED of claim 17 wherein the protecting logic of the IED is further configured to confirm any negative jump in current detected by the IED by confirming receipt of positive current jump information from at least one other IED coupled to the faulted line section.
 22. The IED of claim 21 wherein the protection logic of the IED is further configured to generate a fault confirmation signal based on the confirmation of the negative current jump, and to communicate the fault confirmation signal to other IEDs coupled to the faulted line section.
 23. The IED of claim 14 wherein the protection logic of the IED is further configured to confirm receipt of a fault confirmation signal from all other IEDs coupled to the faulted line section.
 24. The IED of claim 14 wherein the protection logic of the IED is further configured to generate a fault confirmation signal if the IED does not detect either a negative current jump or a positive current jump in the faulted line section in response to communication of a positive current jump from another IED coupled to the faulted line section.
 25. The IED of claim 14 wherein the protection logic of the IED is further configured to use at least one of a ground and a phase overcurrent measurement to confirm any fault detection determined based on negative and positive current jumps communicated between IEDs coupled to the faulted line section.
 26. A method of isolating a fault in a power distribution feeder system have a plurality of power sources and a plurality of switching components coupled to the power sources by a plurality of line sections, the method including: providing an intelligent electronic device (IED) coupled to each switching component and configured to monitor any line section coupled to the switching component; and employing a first IED to: detect a jump in current on a faulted line section; communicate the jump in current to other IEDs coupled to the faulted line section; receive information from the other IEDs coupled to the faulted line section regarding any jump in current detected by the other IEDs; employ the received information from the other IEDs to confirm a fault in the faulted line section; and issue a trip command to isolate the faulted line section based on the current jump detected by the first IED and current jump information received from other IEDs coupled to the line section.
 27. The method of claim 26 further comprising employing the first IED to generate a fault detection signal based on a positive current jump detected by the first IED and negative current jumps detected by other IEDs coupled to the faulted line section.
 28. The method of claim 26 further comprising employing the first IED to confirm any positive jump in current detected by the first IED by confirming receipt of negative current jump information from other IEDs coupled to the faulted line section.
 29. The method of claim 26 further comprising employing the first IED to confirm any negative jump in current detected by the first IED by confirming receipt of positive current jump information from at least one other IED coupled to the faulted line section.
 30. The method of claim 26 further comprising employing the first IED to confirm receipt of a fault confirmation signal from all other IEDs coupled to the faulted line section.
 31. The method of claim 26 further comprising employing the first IED to generate a fault confirmation signal if the first IED does not detect either a negative current jump or a positive current jump in the faulted line section in response to communication of a positive current jump from another IED coupled to the faulted line section.
 32. The method of claim 26 further comprising employing the first IED to use at least one of a ground and a phase overcurrent measurement to confirm any fault detection determined based on negative and positive current jumps communicated between IEDs coupled to the faulted line section. 